In automotive transmissions employing hydrodynamic drive devices, either of the fluid coupling type or the torque converter type, use has been made of lock-up clutches for so locking the drive shaft to the driven shaft as to afford a direct mechanical drive in which the action of the hydrodynamic drive device is effectively bypassed. Various types of lock-up clutches have been employed with varying degrees of success.
Such lock-up clutches generally require some type of selector valve or control valve system to actuate engagement of the clutch during operation of the torque converter. Such a system may utilize a manually controlled selector valve including a direct drive clutch valve for actuation of the direct drive or lock-up clutch. Other control systems are known for automatically operating a fluid actuated clutch in which clutch engagement is controlled by a variable pressure derived from the rotational speed of a vehicle engine and the torque load applied to such an engine so that a regulated rate of pressure can be produced for operating the clutch. However, these systems are generally complicated in arrangement and operation and most do not provide a satisfactory control system whereby all valves cooperate in a simple and satisfactory manner to produce an automatic control system for operating a lock-up clutch. The present invention obviates many of the problems of prior clutch control in a simplified and efficient manner.
The present invention relates to a controlled lock-up clutch for a torque converter in an automotive vehicle that is interposed between the impeller and the turbine of the torque converter for an automatic transmission. The lock-up clutch may be of any conventional design, here shown as a multiplate clutch, and clutch lock-up and unlocking is controlled at a torque converter speed ratio design point by the stator movement and loading.
The present invention also comprehends the provision of a controlled lock-up clutch for a torque converter of a vehicle automatic transmission utilizing a simplified valve system. A two-position rotary valve is mounted on a shaft as an inner race of a one-way clutch, with the outer shell of the stator providing the outer clutch race. When the stator tends to freewheel, the valve is biased into one valve position, whereas when the one-way clutch locks due to the stator force reaction from the converter torque multiplication, the stator and locked one-way clutch act to move the valve to its alternate position.
The present invention further comprehends the provision of a controlled lock-up clutch for an automatic torque converter transmission of an automotive vehicle wherein the direct drive accomplished by the clutch lock-up will provide improved fuel economy and emissions performance as compared with conventional torque converter transmissions without lock-up or with lock-up in third gear only.
Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.